BANGKOK, Jan 19 (Reuters) - Thailand’s government defended its coronavirus vaccine strategy on Tuesday against opposition criticism that it is too reliant on a company owned by King Maha Vajiralongkorn.

The attack by banned opposition politician Thanathorn Juangroongruangkit came as Thailand battles its biggest rise in infections and after months of youth-led protests that brought a rare challenge to the monarchy. Criticising the royal family is illegal.

"These baseless and inaccurate accusations shouldn’t be linked to the work of the institution we revere and love," said Nakorn Premsri, director of the National Vaccine Institute, referring to the monarchy.

He said that royally-owned Siam Bioscience had been the most obvious choice of many companies considered for technology transfer from pharmaceutical firm AstraZeneca to make 200 million vaccine doses each year for Thailand and other nations.

Siam Bioscience is wholly owned by a subsidiary of the Crown Property Bureau, which manages tens of billions of dollars in investments under the king’s personal control.

Thailand has ordered 61 million doses of the AstraZeneca vaccine, which will be ready from June, as well as 2 million doses from China's Sinovac, to be administered from next month.

Thanathorn made his comments on Facebook Live on Monday at an event titled "Royal Vaccine: Who Benefits and Who Doesn't?"

He made no accusations of impropriety against AstraZeneca but said Siam Bioscience lacked vaccine-making experience and the government was relying on it too heavily.

Siam Bioscience's managing director, Songpon Deechongkit, declined to comment on the criticism.

"We want to focus on our responsibility to produce the vaccine in time, with quality, with the appropriate amount," Songpon told Reuters.

AstraZeneca's representative in Thailand could not be reached.

On Tuesday, a hashtag that translates as #royalvaccine trended on Twitter in Thailand with more than 300,000 posts.

Asked about Thanathorn's criticism, Prime Minister Prayuth Chan-ocha told reporters: "It’s all distorted and not factual at all. I will order prosecution for anything false that gets published, whether in media or social media."

Thailand has suffered less than most countries its size from the pandemic, but a second wave of infections began in December. It has had 12,594 cases and 70 deaths. (Reporting by Panu Wongcha-um, Patpicha Tanakasempipat, Chayut Setboonsarng and Panarat Thepgumpanat; Writing by Kay Johnson; Editing by Matthew Tostevin and Clarence Fernandez)